So i just purchased some Sugino RD cranks from harris and got the 165mm, figuring that with the shorter arm length i'd be less likely to strike the ground on a turn. I get them in today and realize that although they are shorter than my 170mm when judge from hole to hole, they are actually 10mm longer overall if you measure to the end of the arm. so overall, old cranks = 180mm, sugino rd=190mm.
obnoxious

but...the pedals are what will strike the ground, and they'll be 5mm closer to the BB.

I posted about this in January I believe and made a graphic:



I no longer run non-track cranks. Sugino 75's here.

Will you look at that. I'm running the purportedly-165mm RDs on my conversion. I'll have to look at this when I get home, but the picture of them on Harris' site confirms your graphics, absntr. No pedal strike for me, though, so I guess it's a victimless crime.

aesthetics. bah!

It doesn't effect the actual usage of the cranks -- pedal strike won't occur since it's the position of the pedal that matters, not the actual length of the crank (which would never hit the ground at any rideable angle, if at all).

I'm assuming that Sugino found a cheaper way to make an affordable crank by casting only one size for the cranks and just drilling the hole for the desired lengths they made available.

it is a bit deceiving but after a couple hundred miles on my rd's (on a road frame with lower bb no less) i haven't had any problems at all.

my 155mm bulletproof cranks have a similar actual arm length to the 160 and maybe even 165mm cranks they make, just that the holes are drilled closer to the center of the arm.

Plus it's better for bashing your way through rocks n' logs, right?

edit: sorry, I'm being silly. seriously now, Turd, how do you like 155mm crankarms? that seems real short, but i imagine it helps spinning. i noticed the many lengths available for the Bulletproofs and it piqued my interest.

Yes, do not worry about the length of the arm! Measure the angle made from the ground by the line going from the tire track line and the bottom of the crank arm, and you'll find its way over 45 degrees, which you can't really lean past anyway. Its the pedal that will always hit the ground NOT the bottom of the crank.

Its not deceptive, its geometry!

peace,
sam

yeah, i realize the longer arm isn't gonna hit... but it's the principle! haha. it just looks weird.